The present invention relates to belt conveyors for carrying free-flowing materials such as coal, ore, or the like, in which the conveyed material is prevented from flowing off of the sides of the belt, and, more particularly, to such belt conveyors that employ side skirts contacting the sides of the belt along their length to prevent the conveyed material from flowing off of the belt.
Belt conveyors are commonly used for the transport of coal, ores, or similar free-flowing materials. During transport of such free-flowing materials, spillage of the transported material over the edges of the belt is a common and often significant problem. Thus, in many belt conveyor systems, the support plates for the belt are troughed to help alleviate the problem of spillage. Troughing, however, is limited by the flexibility of the belt material. As a second solution to the problem of spillage, a sealing skirt is frequently used. These skirts, typically made of rubber, are hung so that their bottom edges are positioned against the conveyor belt along the edges of the conveyor belt, providing a seal against the belt that prevents spillage.
These skirts, however, are prone to rapid wear and deterioration. Friction is created where the skirt contacts the belt; not only does this cause the skirt to wear rapidly, but the belt also may show premature wear. Moreover, particles often become lodged between the skirt and the belt, further accelerating wear of both the belt and conveyor. Thus, frequent and time-consuming replacement of the skirts is necessary. To address this problem, prior art devices have used a floating skirt. In a floating skirt arrangement, the skirt moves downwardly, under the force of gravity, as it wears. The top of the skirt is not held rigidly but is held in a bracket that allows for the downward movement of the skirt as it wears. Use of such a sealing skirt is taught in Holwick U.S. Pat. No. 2,665,795, issued on Jan. 12, 1954.
The floating skirt arrangement, however, presents significant problems of its own. Because the floating skirt is free to move in a vertical plane, large particles may become wedged between the skirt and belt, and actually force the skirt upward, allowing particles to spill from the conveyor. Moreover, wear does not occur uniformly, and portions of the skirt having worn more rapidly than others may rise above the belt. Therefore, it would be desirable to provide a skirt that prevents the spillage of coal from a conveyor belt and compensates for the wearing of said skirt while uniformly maintaining an appropriate seal at all points along both sides of the belt.
Maintenance expense and downtime are the principal problems that prior art inventions seek to address. Thus, it is further desirable to provide a sealing skirt that is easily replaced, minimizing conveyor downtime.